Abstract

1. Theobromine, in the form of theocalcin and of theobromine sodio-salicylate, and caffeine were injected intravenously and administered through a stomach tube to cats. The animals were exsanguinated after varying intervals of time and the concentration of theobromine and caffeine in the blood was determined.

2. The concentration in the blood stream falls rapidly immediately after the intravenous injection of caffeine or theobromine, and more slowly after 5 minutes.

3. The concentration in the blood after an interval of half an hour or more following the oral administration approximates that after similar intervals following intravenous injection. These results suggest that the intravenous injection of these substances is unnecessary as a rule.